Capacitor, capacitor mounting structure, and taped electronic component series

ABSTRACT

In a capacitor main body, a dimension along the thickness direction of a first region where a first inner electrode and a second inner electrode are provided is t 1 , a dimension along the thickness direction of a second region that is positioned on the side of a first main surface relative to the first region is t 2 , and a dimension along the thickness direction of a third region that is positioned on the side of a second main surface relative to the first region is t 3 . A condition of t 2 /t 1 &gt; about 0.15 and a condition of t 3 /t 1 &gt; about 0.15 are satisfied.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to capacitors, capacitor mountingstructures, and taped electronic component series.

2. Description of the Related Art

At present, capacitors such as multilayer ceramic capacitors are used invarious types of electronic components.

When a voltage applied to a multilayer ceramic capacitor varies, themultilayer ceramic capacitor is distorted in some cases. The distortionof the multilayer ceramic capacitor is transferred to a circuit board onwhich the multilayer ceramic capacitor is mounted, via a bondingmaterial. This causes the circuit board to vibrate. In a case where avibration frequency of the circuit board is about 20 Hz to 20 kHz, thevibration of the circuit board is recognized as a sound. A soundgenerated at this audible frequency band is called “acoustic noise”.This acoustic noise has been a problem in various types of electronicapparatuses such as television sets, personal computers, mobilecommunication terminals such as cellular phones, and so on.

Japanese Unexamined Patent Application Publication No. 2013-38332discloses that acoustic noise can be suppressed by making, in acapacitor region where a first inner electrode and a second innerelectrode oppose each other, the thickness of a suppression regionlocated on one side of the capacitor region be larger than the thicknessof a suppression region located on the other side thereof.

It has been desired to further suppress acoustic noise in capacitormounting structures.

SUMMARY OF THE INVENTION

Accordingly, preferred embodiments of the present inventionsignificantly reduces or prevents acoustic noise in capacitor mountingstructures.

A capacitor according to an aspect of various preferred embodiments ofthe present invention includes a capacitor main body, a first innerelectrode, and a second inner electrode. The capacitor main bodyincludes a first main surface, a second main surface, a first sidesurface, a second side surface, a first end surface, and a second endsurface. The first main surface and the second main surface extend alonga longitudinal direction and a width direction. The first side surfaceand the second side surface extend along the longitudinal direction anda thickness direction. The first end surface and the second end surfaceextend along the width direction and the thickness direction. The firstinner electrode and the second inner electrode are provided in thecapacitor main body. The first inner electrode and the second innerelectrode oppose each other via a ceramic section. The ceramic sectionincludes ferroelectric ceramics. In the capacitor main body, a dimensionalong the thickness direction of a first region where the first andsecond inner electrodes are provided is taken as t1. In the capacitormain body, a dimension along the thickness direction of a second regionthat is positioned on the first main surface side relative to the firstregion is taken as t2. In the capacitor main body, a dimension along thethickness direction of a third region that is positioned on the secondmain surface side relative to the first region is taken as t3. Acondition of t2/t1>about 0.07 and a condition of t3/t1>about 0.07 arepreferably satisfied.

In the capacitor according to another aspect of various preferredembodiments of the present invention, in the case where a shortestdistance along the width direction from a portion where both the firstand second inner electrodes of the capacitor main body are provided tothe first side surface is taken as w2, and a shortest distance along thewidth direction from the portion where both the first and second innerelectrodes of the capacitor main body are provided to the second sidesurface is taken as w3, it is preferable for t2 and t3 to be greaterthan w2 and w3, respectively.

In the capacitor according to another aspect of various preferredembodiments of the present invention, it is preferable for a conditionof about 2.0>t3/t2>about 0.5 to be satisfied.

In the capacitor according to another aspect of various preferredembodiments of the present invention, it is preferable for t2 and t3 tobe equal or substantially equal to each other.

In the capacitor according to another aspect of various preferredembodiments of the present invention, it is preferable for the firstinner electrode and the second inner electrode to oppose each other inthe thickness direction.

A capacitor mounting structure according to another aspect of variouspreferred embodiments of the present invention includes the capacitoraccording to the aforementioned aspects of various preferred embodimentsof the present invention and a mounting board on which the capacitor ismounted. In the structure, the capacitor is mounted so that the secondmain surface opposes the mounting board.

A taped electronic component series according to another aspect ofvarious preferred embodiments of the present invention includes thecapacitor according to the aforementioned aspects of various preferredembodiments of the present invention, and a tape including a pluralityof recesses that are arranged along the longitudinal direction and ineach of which the capacitor is accommodated. The capacitor is disposedso that the second main surface thereof opposes a bottom surface of therecess.

According to the various aspects of various preferred embodiments of thepresent invention, acoustic noise is significantly reduced or preventedin capacitor mounting structures.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a capacitor according to apreferred embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view taken along a line II-II inFIG. 1.

FIG. 3 is a schematic cross-sectional view taken along a line III-III inFIG. 1.

FIG. 4 is a schematic cross-sectional view of a taped electroniccomponent series according to a preferred embodiment of the presentinvention.

FIG. 5 is a schematic cross-sectional view of a capacitor mountingstructure according to a preferred embodiment of the present invention.

FIG. 6 is a schematic cross-sectional view of a capacitor according to avariation of a preferred embodiment of the present invention.

FIG. 7 is a photograph of a cross section of an actually manufacturedcapacitor, taken along the width direction and the thickness directionat the center of the capacitor in the longitudinal direction.

FIG. 8 is a diagram schematically illustrating expansion/contraction ofa capacitor in the case where both t2/t1 and t3/t1 are smaller.

FIG. 9 is a diagram schematically illustrating expansion/contraction ofa capacitor in the case where t2/t1 is larger while t3/t1 is smaller.

FIG. 10 is a diagram schematically illustrating expansion/contraction ofa capacitor in the case where both t2/t1 and t3/t1 are larger.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, examples of various preferred embodiments of the presentinvention will be described. Note that, however, the preferredembodiments described below are merely examples. The present inventionis not intended to be limited to the following preferred embodiments inany way.

Further, in the drawings referred to in the description of preferredembodiments and the like, members having functions that are identical orsubstantially identical are given identical reference numerals. Thedrawings referred to in the description of preferred embodiments and thelike are schematic depictions, and as such the ratios of dimensions andso on of objects depicted in the drawings may differ from the actualratios of dimensions and so on of those objects. The ratios ofdimensions and so on of the objects may differ from drawing to drawingas well. The specific ratios of dimensions and so on of objects shouldbe understood in consideration of the following descriptions.

FIG. 1 is a schematic perspective view of a capacitor according to apreferred embodiment of the present invention. FIG. 2 is a schematiccross-sectional view taken along a line II-II in FIG. 1. FIG. 3 is aschematic cross-sectional view taken along a line III-III in FIG. 1.

A capacitor 1 illustrated in FIGS. 1 through 3 is a multilayer ceramiccapacitor. Various preferred embodiments of the present invention can bepreferably applied to the capacitor 1 having large electrostaticcapacity that is likely to cause the generation of acoustic noise, inparticular, preferably applied to the capacitor 1 having electrostaticcapacity of no less than about 1 μF, about 10 μF, and so on.

The capacitor 1 includes a capacitor main body 10. The capacitor mainbody 10 preferably has a substantially parallelepiped shape. Assume thatthis substantially parallelepiped shape includes, in addition to aparallelepiped, a parallelepiped whose corners, ridge lines, and so onare chamfered, rounded, and so on.

The capacitor main body 10 includes a first main surface 10 a, a secondmain surface 10 b, a first side surface 10 c, a second side surface 10d, a first end surface 10 e, and a second end surface 10 f (first andsecond end surfaces 10 e and 10 f can be seen in FIG. 2). The first andsecond main surfaces 10 a and 10 b both extend along a longitudinaldirection L and a width direction W. The longitudinal direction L andthe width direction W are perpendicular or substantially perpendicularto each other. The first and second side surfaces 10 c and 10 d bothextend in the longitudinal direction L and a thickness direction T. Thethickness direction T is perpendicular or substantially perpendicular toboth the longitudinal direction L and the width direction W. The firstand second end surfaces 10 e and 10 f both extend in the width directionW and the thickness direction T.

It is preferable for the dimension of the capacitor main body 10 alongthe longitudinal direction L to be about 0.6 mm to about 1.8 mm, forexample. It is preferable for the dimension of the capacitor main body10 along the width direction W to be about 0.3 mm to about 1.0 mm, forexample. It is preferable for the dimension of the capacitor main body10 along the thickness direction T to be about 0.3 mm to about 1.2 mm,for example.

The capacitor main body 10 is preferably configured with ferroelectricceramics so as to obtain large electrostatic capacity. As specificexamples of dielectric ceramics, BaTiO₃, CaTiO₃, SrTiO₃, and so on arecapable of being used. Based on the characteristics that the capacitor 1is required to have, accessory components such as Mn compounds, Mgcompounds, Si compounds, Fe compounds, Cr compounds, Co compounds, Nicompounds, rare earth compounds, and so on, for example, may beappropriately added to the capacitor main body 10. It is preferable forrelative permittivity of the ferroelectric ceramics to be no less thanabout 2000, and more preferable to be no less than about 3000, forexample. In this case, electrostatic capacity of no less than about 1μF, about 10 μF, or the like is capable of being realized within theabove-mentioned dimensions of the capacitor main body 10. Becauseacoustic noise is likely to be generated in the capacitor 1 having beendiscussed so far, various preferred embodiments of the present inventionare preferably applied thereto.

In the case where a Mn compound is added to the ferroelectric ceramics,it is preferable for the content of Mn in the dielectric ceramics to beno more than about 0.5 mol part with respect to BaTiO₃ of 100 mol part,and more preferable to be no more than about 0.2 mol part, for example.In order to improve reliability of the capacitor 1, it is preferable forthe Mn compound to be no less than about 0.05 mol part, for example.

As shown in FIGS. 2 and 3, there are provided a plurality of first innerelectrodes 11 and a plurality of second inner electrodes 12 inside thecapacitor main body 10. The first inner electrode 11 and the secondinner electrode 12 oppose each other via a ceramic section 10 g. In thepresent preferred embodiment, the first inner electrodes 11 and thesecond inner electrodes 12 are alternately provided along the thicknessdirection T. The first inner electrodes 11 and the second innerelectrodes 12 oppose each other via the ceramic sections 10 g in thethickness direction T. However, the present invention is not intended tobe limited to this configuration. In the present invention, the firstinner electrodes and the second inner electrodes may oppose each otherin the width direction or in the longitudinal direction, for example.

Various preferred embodiments of the present invention are preferablyapplicable, in particular, to a capacitor in which no less than 350sheets of ceramic sections 10 g are laminated while being sandwichedbetween the first inner electrodes 11 and the second inner electrodes12. In other words, it is preferable for the number of the first andsecond inner electrodes 11 and 12 to be no less than 350 in total. Inorder to encompass no less than 350 sheets of ceramic sections 10 g inthe capacitor main body with a limited thickness, it is preferable forthe thickness of the ceramic section 10 g to be no more than about 1 μm,for example. In the case where the thickness of the ceramic section 10 gis no more than about 1 μm, acoustic noise is likely to be generatedbecause electrostatic capacity per unit area in a surface of the ceramicsection 10 g perpendicular or substantially perpendicular to thethickness direction T becomes larger. Accordingly, various preferredembodiments of the present invention are preferably applicable to thecapacitor 1 whose electrostatic capacity is no less than about 1 μF andwhose ceramic section 10 g is no more than about 1 μm in thickness, aswell as the capacitor 1 whose electrostatic capacity is no less thanabout 10 μF and whose ceramic section 10 g is no more than about 1 μm inthickness, for example.

The first inner electrodes 11 are provided along the longitudinaldirection L and the width direction W. The first inner electrodes 11extend to the first end surface 10 e, but do not extend to any of thefirst and second main surfaces 10 a and 10 b, the first and second sidesurfaces 10 c and 10 d, and the second end surface 10 f.

The second inner electrodes 12 are provided along the longitudinaldirection L and the width direction W. The second inner electrodes 12extend to the second end surface 10 f, but do not extend to any of thefirst and second main surfaces 10 a and 10 b, the first and second sidesurfaces 10 c and 10 d, and the first end surface 10 e.

The first inner electrodes 11 and the second inner electrodes 12 can beindividually configured with at least one type of material such as Pt,Au, Ag, Cu, Ni, Cr, or the like, for example.

A first outer electrode 13 is provided on the first end surface 10 e.The first outer electrode 13 extends from an area on the first endsurface 10 e onto the first and second main surfaces 10 a, 10 b and thefirst and second side surfaces 10 c, 10 d. The first external electrode13 is connected with the first inner electrodes 11 at the first endsurface 10 e.

A second outer electrode 14 is provided on the second end surface 10 f.The second outer electrode 14 extends from a portion on the second endsurface 10 f onto the first and second main surfaces 10 a, 10 b and thefirst and second side surfaces 10 c, 10 d. The second external electrode14 is connected with the second inner electrodes 12 at the second endsurface 10 f.

The first outer electrode 13 and the second outer electrode 14 can beindividually configured with at least one type of material such as Pt,Au, Ag, Cu, Ni, Cr, or the like, for example.

FIG. 4 is a schematic cross-sectional view of a taped electroniccomponent series according to a preferred embodiment of the presentinvention.

As shown in FIG. 4, a taped electronic component series 2 is a member inwhich the plurality of capacitors 1 are fixed by taping. The tapedelectronic component series 2 includes an elongated tape 20. The tape 20includes an elongated carrier tape 21 and an elongated cover tape 22.The carrier tape 21 includes a plurality of recesses 21 a provided atintervals along the longitudinal direction. The cover tape 22 isarranged on the carrier tape 21 so as to cover the plurality of recesses21 a. Each of the plurality of recesses 21 a accommodates the capacitor1. The plurality of capacitors 1 are disposed so that the second mainsurface 10 b of each of the capacitors 1 faces the side of a bottomsurface of the recess 21 a. With this, the plurality of capacitors 1 areheld with the first main surface 10 a side thereof being bonded, andmounted with the second main surface 10 b side thereof facing the sideof a wiring board.

FIG. 5 is a schematic cross-sectional view of a capacitor mountingstructure according to a preferred embodiment of the present invention.

As shown in FIG. 5, a capacitor mounting structure 3 includes thecapacitor 1 and a mounting board 30. The capacitor is mounted on themounting board 30 so that the second main surface 10 b faces themounting board 30 side.

The first and second internal electrodes 11 and 12 are provided in aportion of the capacitor main body 10 in the thickness direction T. Thecapacitor main body 10 includes a first region A1 in which the first andsecond inner electrodes 11 and 12 are provided, a second region A2positioned on the first main surface 10 a side relative to the firstregion A1, and a third region A3 positioned on the second main surface10 b side relative to the first region A1. The first region A1 is calledan effective region because this region exhibits the function of acapacitor. On the other hand, the second and third regions A2 and A3 areeach called a non-effective region because these regions do not exhibita function of a capacitor. Since the second and third regions A2 and A3are thicker in dimension than a general capacitor having largeelectrostatic capacity, the second and third regions A2 and A3 areformed preferably by laminating a plurality of sheets of dielectricceramics, each of which is thicker in dimension than the ceramic section10 g.

Here, as illustrated in FIG. 3, a dimension of the first region A1 alongthe thickness direction T is taken as t1. A dimension of the secondregion A2 along the thickness direction T is taken as t2. A dimension ofthe third region A3 along the thickness direction T is taken as t3. Adistance along the width direction from a portion of the capacitor mainbody 10 where both the first and second inner electrodes 11 and 12 areprovided to the first side surface 10 c is taken as w2, and a distancealong the width direction from a portion of the capacitor main body 10where both the first and second inner electrodes 11 and 12 are providedto the second side surface 10 d is taken as w3. It is preferable for t2and t3 to be respectively larger than w2 and w3. In other words, it ispreferable for t2 and t3 to be each larger than the greater one of w2and w3. This is in contrast to a general case as follows. That is, inthe case of a capacitor where the dimension of the capacitor main body10 along the longitudinal direction L is no more than about 1.7 mm, thedimension thereof along the width direction W is no more than about 0.9mm, and the electrostatic capacity is no less than about 1 μF, forexample, w2 and w3 are generally made larger than t2 and t3 in order toensure electrostatic capacity, moisture resistance, and manufactureprecision.

Note that t2 and t3 can be measured in the following manner: that is,the capacitor 1 is polished so as to expose a cross section passing thecenter of the capacitor main body 10 and perpendicular or substantiallyperpendicular to the longitudinal direction L, then t2 and t3 can bemeasured at a central position of the cross section in the widthdirection W. Meanwhile, w2 and w3 can be measured in the followingmanner: that is, the capacitor 1 is polished so as to expose a crosssection passing the center of the capacitor main body 10 andperpendicular or substantially perpendicular to the longitudinaldirection L, then w2 and w3 can be measured at a central position of thecross section in the thickness direction T.

Conventionally, in a mounting structure where a capacitor is mounted ona mounting board so that the second main surface faces the mountingboard, it is preferable for the dimension of thickness of the thirdregion to be large from the standpoint of suppressing acoustic noise; onthe other hand, it is assumed that the dimension of thickness of thesecond region has little influence on the acoustic noise. Meanwhile,from the standpoint of increasing electrostatic capacity of thecapacitor, it is preferable for the dimension of thickness of the firstregion to be large. Accordingly, in order to suppress the reduction inelectrostatic capacity of the capacitor and to suppress the acousticnoise by making the dimension of thickness of the third region largerand making the dimension of thickness of the second region smaller,design in which, of the second and third regions, only the third regionis allowed to have a larger dimension of thickness, is generally used.

However, the inventors discovered through elaborate research thatacoustic noise is further reduced or prevented by making the secondregion, in addition to the third region, thicker. As such, in the caseof the capacitor 1 according to the present preferred embodiment,because a condition of t2/t1>about 0.07 and a condition of t3/t1>about0.07 are both satisfied, acoustic noise is further reduced or preventedin the mounting structure 3 where the capacitor 1 is mounted.

The following can be conceived of in the conventional design conceptdiscussed above: that is, of the thickness dimension that thenon-effective regions are allowed to have depending on a requiredelectrostatic capacity and the external dimensions of the capacitor, apossible maximum amount thereof is assigned to the third region, whereasa possible least amount thereof is assigned to the second region.However, as a result of the elaborate research, the inventors discoveredthat acoustic noise is not sufficiently suppressed if the thicknessdimension of the second region is made excessively small. From thestandpoint of sufficiently reducing or preventing the acoustic noise, itis preferable for a condition of t1/t0>about 0.6 and a condition of1.2>t3/t2>about 0.8 to be satisfied in the case where a dimension of thecapacitor main body 10 in the thickness direction T is taken as t0.

As in the past, if the design in which the thickness dimension t2 of thesecond region is small, and only the thickness dimension t3 of the thirdregion is large is used, in order to make the first main surface opposethe mounting board, it is necessary to identify the first main surfaceand the second main surface, in other words, necessary todirectionally-align the capacitor while identifying the upper and lowersurfaces thereof. Because of this, as described in Japanese UnexaminedPatent Application Publication No. 2013-38332, for example, the innerelectrodes are needed to be exposed, or an identification mark needs tobe added in a manner such that layers having different colors areprovided on an outer surface of the capacitor, and so on. However, theaddition of such identification mark has caused deterioration incharacteristics, reliability, and so on of the capacitor, and complexityin the manufacture of the capacitor.

Meanwhile, in the case where both t2 and t3 satisfy the aboveconditions, acoustic noise is significantly reduced or prevented in anyof the cases where the first main surface opposes the mounting board andwhere the second main surface opposes the mounting board. This makes itunnecessary to identify the first main surface and the second mainsurface, in other words, unnecessary to identify the upper and the lowersurfaces when mounting the capacitors 1, arranging the capacitors in thetape 20, and so on. From this standpoint, it is preferable for t2 and t3to satisfy a condition of 2.0>t3/t2>about 0.5, for example. In thiscase, there is only a slight difference in effectiveness ofsignificantly reducing or preventing the acoustic noise between the casewhere the first main surface opposes the mounting board and the casewhere the second main surface opposes the mounting board. It ispreferable for t2 and t3 to be equal or substantially equal to eachother. The expression of “t2 and t3 to be equal or substantially equalto each other” means that t3 is about 0.9 to about 1.1 times t2, forexample.

In order to further effectively reduce or prevent acoustic noise, it isfurther preferable for a condition of t2/t1>0.15 and a condition oft3/t1>0.15 to be satisfied. However, if t2/t1 and t3 /t1 are too large,the electrostatic capacity of the capacitor 1 becomes too small in somecases. Alternatively, there is a case in which the mounting posture ofthe capacitor 1 becomes unstable because the thickness dimension t0 ofthe capacitors 1 becomes too large in an attempt to ensure theelectrostatic capacity of the capacitor 1. As such, it is preferable fora condition of t2/t1<about 0.3 to be satisfied, for example. It ispreferable as well for a condition of t3/t1<about 0.3, for example, tobe satisfied.

In the case where a dimension of the capacitor main body 10 along thewidth direction W is taken as w0, it is preferable for t0 and w0 to beequal or substantially equal to each other. In this case, the posturestability of the capacitor 1 is improved at a time of mounting thecapacitor 1 and after the mounting. At this time, mounting or taping ofthe capacitors 1, while identifying the main surfaces and the sidesurfaces or aligning the arrangement direction thereof, can be carriedout with magnetic force making use of the surface direction of the innerelectrodes. Here, the expression of “t0 and w0 to be equal orsubstantially equal to each other” means that w0 is about 0.9 to about1.1 times t0, for example.

However, t0 may be larger than w0. In this case, such an advantage isachieved that the mounting or taping of the capacitors 1, whileidentifying the main surfaces and the side surfaces or aligning thearrangement direction thereof, can be carried out with ease due todifference in the outer shape.

Depending on design conditions of the capacitor main body 10, the mainsurfaces and the side surfaces can be identified by difference in colordepth between the main surfaces and the side surfaces. That is, in thecase where at least one of W2 and w3 is smaller in comparison with t2and t3, the inner electrodes 11 and 12 can be seen transparently fromthe side surfaces 10 c and 10 d, as shown in FIG. 6, and the color ofthe side surfaces 10 c and 10 d becomes deeper than that of the mainsurfaces. Alternatively, diffusion of inorganic components contained inthe inner electrodes 11 and 12 makes the color of the side surfaces 10 cand 10 d deeper than that of the main surfaces 10 a and 10 b. Furtheralternatively, the color of side gap portions located between the sidesurfaces 10 c, 10 d and the effective region (first region A1) becomesdeeper than that of the second and third regions A2 and A3 so that thecolor of the side surfaces 10 c and 10 d becomes deeper than that of themain surfaces 10 a and 10 b. The color of the side surfaces 10 c and 10d becomes deep in a belt-shaped pattern extending in the longitudinaldirection, corresponding to the inner electrodes 11 and 12. In FIG. 6,the portion having a deep color is indicated by hatching.

The following is considered to be a reason why the color of the side gapportions becomes deeper than that of the second and third regions A2 andA3. That is, because the side gap, which is thin, is close to the outersurface, pores in the side gap portions are likely to escape therefrom.In contrast, pores in the second and third regions A2 and A3, which arethick, are unlikely to escape therefrom and likely to remain. If thepores remain, color looks lighter. This is because irregular reflectionof light is caused by the remaining pores. As shown in FIG. 7, thethicknesses w2 and w3 of the side gap portions are smaller than thethicknesses t2 and t3 of the second and third regions A2 and A3.Therefore, the remaining rate of the pores in the side gap portions islower than that in the second and third regions A2 and A3, so that thecolor of the side surfaces, which are the outer surfaces of the side gapportions, becomes deeper and the color of the main surfaces, which arethe outer surfaces of the second and third regions A2 and A3 becomeslighter. This makes it possible to distinguish the side surfaces and themain surfaces by the difference in depth of colors.

In order to make clear the difference in depth of colors, it ispreferable for at least one of w2 and w3 to be smaller by no less thanabout 10 μm in comparison with t2 and t3, and more preferable to besmaller by no less than about 30 μm, for example. Alternatively, it ispreferable for at least one of w2 and w3 to be no more than about 80 μm,and more preferable to be no more than 60 μm, for example. Furtheralternatively, it is preferable to make the overall color of thedielectric ceramics lighter so as to make clear the difference in colorsbetween the side surfaces and the main surfaces. The color of dielectricceramics becomes lighter while changing from brown toward white as thecontent of Mn is smaller. This makes clear the difference in color.Accordingly, to identify the side surfaces and the main surfaces by thedifference in colors, it is preferable for the content of Mn to be nomore than about 0.5 mol part with respect to BaTiO₃ of 100 mol part, forexample. It is preferable as well for the content of Mn to be no morethan about 0.2 mol part with respect to BaTiO₃ of 100 mol part, forexample.

In particular, in the case where the inner electrodes 11, 12 include Nias a metal component in the main components, Ni diffuses into adielectric material so that the difference in depth of color is madeeven more clear. Also in this case, the color of the side surfaces 10 cand 10 d is deeper toward black than the color of the main surfaces 10 aand 10 b.

The color of the side surfaces 10 c and 10 d and the color of the mainsurfaces 10 a and 10 b can be confirmed visually or under an opticalmicroscope. Observing a cross section of the capacitor main body 10under an optical microscope makes it possible to confirm the differencein color. The aforementioned remaining rate of the pores can be measuredas an area ratio by observing a cross section of the capacitor main body10 using a scanning electron microscope (SEM). Note that, however, thereis a case in which a difference in remaining rate, which causes adifference in color, is included within a measurement error and cannotbe recognized. A state of Ni distribution due to the diffusion can beconfirmed from an element mapping image obtained through observationusing an energy dispersive X-ray (EDX) analyzer device that is attachedto the SEM.

The content of Mn can be measured in the following manner, for example.That is, forty multilayer ceramic capacitors 1 are respectively immersedin a sample bottle storing about 30 mL of a 0.2 mol/L adipic acidsolution. The sample bottle is sealed and placed for about 120 hours ina standstill state at a temperature of about 85° C. After cooling, themultilayer ceramic capacitors 1 are taken out and washed by pure wateruntil the adipic acid solution comes to the amount of 50 mL.Subsequently, ceramic components contained in 5 mL of an eluted liquidof the 50 mL adipic acid solution are quantified with an ICP emissionspectrometry so as to obtain a total amount of eluted elements havingbeen detected in a unit of μmol.

The following can be considered to be a reason why a sound pressure ofacoustic noise is further reduced or prevented when both t2/t1 and t3/t1are made larger than when only one of them is made larger. As can beunderstood by comparing FIG. 8 with FIG. 9, in the case where only t2/t1is made larger, a constraint force against the second region of thecapacitor main body becomes strong. With this, on the first mainsurface, a force that acts on the exterior in the thickness direction Tfrom the capacitor becomes weak; reacting to this, on the second mainsurface, a force that acts on the exterior in the thickness direction Tfrom the capacitor becomes strong. As a result, since a force appliedtoward the capacitor in the longitudinal direction L on the second mainsurface becomes weak, a mounting board on which the capacitor is mountedis prevented from being deformed. On the other hand, in the case whereonly t3/t1 is made larger, a distance between the first region of thecapacitor main body and the second main surface becomes longer. As such,the second main surface is distanced from the first region wheredistortion is generated, which makes the force applied toward thecapacitor in the longitudinal direction L on the second main surfaceweak. As a result, the mounting board on which the capacitor is mountedis prevented from being deformed. As shown in FIG. 10, in the case whereboth t2/t1 and t3/t1 are made larger, the reaction to the constraintrelated to t2/t1 and the action caused by the thickness related to t3/t1produce a synergistic effect, so that the force generated on the secondmain surface and applied toward the capacitor in the longitudinaldirection L is further reduced by an amount which is larger than the sumof the amount in reduction of the force generated on the second mainsurface and applied toward the capacitor in the longitudinal direction Lin the case of making only t2/t1 larger and the amount in reduction ofthe force generated on the second main surface and applied toward thecapacitor in the longitudinal direction L. As such, it can be consideredthat the synergistic effect produced by making both t2/t1 and t3/t1larger significantly reduces or prevents the acoustic noise effectively.It is to be noted that in the present specification, force applied tothe main surfaces along the longitudinal direction L is evaluated in themanner in which a direction of force applied toward the center side ofthe capacitor in the longitudinal direction L is taken as a positivedirection.

Hereinafter, various preferred embodiments of the present invention willbe described in further detail based on specific examples. However, thepresent invention is not intended to be limited to the followingexamples in any way, and can be embodied by making appropriatemodifications thereupon without departing from the spirit and scope ofthe present invention.

FIRST EXAMPLE

Under the following conditions, a capacitor mounting structure wasmanufactured. The sound pressure of acoustic noise of the manufacturedcapacitor mounting structure was measured under the followingpost-firing design conditions.

Capacitor Conditions

Dimensions of the capacitor main body: L dimension was about 1.10 mm, Wdimension was about 0.59 mm, and T dimension was about 0.69 mm.

t1: about 520 μm

t2: about 85 μm

t3: about 85 μm

w2: about 55 μm

w3: about 55 μm

Number of ceramic sections: 391

Electrostatic capacity: about 4.7 μF

Measurement Condition of Acoustic Noise Sound Pressure

The capacitor was mounted on a mounting board using solder so as tomanufacture a sample S. Next, the sample S was placed in an anechoic boxof a measurement instrument, and an AC voltage of about 1 Vpp at afrequency band of about 1 kHz to 6 kHz was applied to the capacitor. Inthis state, acoustic noise was collected by a directional microphonedisposed 3 mm above the multilayer ceramic capacitor of the sample S.Then, a maximum sound pressure level of the sound collected by a soundcollecting meter and an FFT analyzer (CF-5220 manufactured by Ono SokkiCo., Ltd.) was measured.

SECOND EXAMPLE

Aside from setting the following conditions, a capacitor mountingstructure was manufactured and the sound pressure level of acousticnoise thereof was measured in the same manner as in the case of thefirst example.

Dimensions of the capacitor main body: L dimension was about 1.10 mm, Wdimension was about 0.64 mm, and T dimension was about 0.82 mm.

t1: about 700 μm

t2: about 60 μm

t3: about 60 μm

w2: about 50 μm

w3: about 50 μm

Number of ceramic sections: 409

Electrostatic capacity: about 10 μF

THIRD EXAMPLE

Aside from setting the following conditions, a capacitor mountingstructure was manufactured and the sound pressure level of acousticnoise thereof was measured in the same manner as in the case of thefirst example.

Dimensions of the capacitor main body: L dimension was about 1.60 mm, Wdimension was about 0.91 mm, and T dimension was about 1.11 mm.

t1: about 820 μm

t2: about 140 μm

t3: about 140 μm

w2: about 70 μm

w3: about 70 μm

Number of ceramic sections: 524

Electrostatic capacity: about 22 μF

FIRST COMPARATIVE EXAMPLE

A capacitor mounting structure was manufactured and the sound pressureof acoustic noise thereof was measured in the same manner as in the caseof the first example, aside from that t2 and w2 were made equal to eachother, and the T dimension was made smaller accordingly.

SECOND COMPARATIVE EXAMPLE

A capacitor mounting structure was manufactured and the sound pressureof acoustic noise thereof was measured in the same manner as in the caseof the second example, aside from that t2 and w2 were made equal to eachother, and the T dimension was made smaller accordingly.

THIRD COMPARATIVE EXAMPLE

A capacitor mounting structure was manufactured and the sound pressureof acoustic noise thereof was measured in the same manner as in the caseof the third example, aside from that t2 and w2 were made equal to eachother, and the T dimension was made smaller accordingly.

As a result, the sound pressure level of the capacitor in the firstexample was lower than that of the capacitor in the first comparativeexample by about 8.1 dB. The sound pressure level of the capacitor inthe second example was lower than that of the capacitor in the secondcomparative example by about 9.1 dB. The sound pressure level of thecapacitor in the third example was lower than that of the capacitor inthe third comparative example by about 6.5 dB.

Next, in order to clarify the thickness dimension t2 of the secondregion and the thickness dimension t3 of the third region that make itpossible to effectively reduce or prevent acoustic noise, the followingexperiments were carried out.

FOURTH COMPARATIVE EXAMPLE

Aside from setting the following conditions, a capacitor mountingstructure was manufactured and the sound pressure level of acousticnoise thereof was measured in the same manner as in the case of thefirst example. The result is shown in Table 1.

Dimensions of the capacitor main body: L dimension was about 1.75 mm, Wdimension was about 0.85 mm, and T dimension was about 0.85 mm.

t1: about 780 μm

t2: about 40 μm

t3: about 40 μm

t2/t1: about 0.05

t3/t1: about 0.05

w2: about 100 μm

w3: about 100 μm

Number of ceramic sections: 345

Electrostatic capacity: about 10 μF

FOURTH EXAMPLE

Aside from setting the following conditions, a capacitor mountingstructure was manufactured and the sound pressure level of acousticnoise thereof was measured in the same manner as in the case of thefourth comparative example. The result is shown in Table 1.

t1: about 780 μm

t2: about 55 μm

t3: about 55 μm

t2/t1: about 0.07

t3/t1: about 0.07

FIFTH EXAMPLE

Aside from setting the following conditions, a capacitor mountingstructure was manufactured and the sound pressure level of acousticnoise thereof was measured in the same manner as in the case of thefourth comparative example. The result is shown in Table 1.

t1: about 780 μm

t2: about 80 μm

t3: about 80 μm

t2/t1: about 0.1

t3/t1: about 0.1

SIXTH EXAMPLE

Aside from setting the following conditions, a capacitor mountingstructure was manufactured and the sound pressure level of acousticnoise thereof was measured in the same manner as in the case of thefourth comparative example. The result is shown in Table 1.

t1: about 780 μm

t2: about 120 μm

t3: about 120 μm

t2/t1: about 0.15

t3/t1: about 0.15

SEVENTH EXAMPLE

Aside from setting the following conditions, a capacitor mountingstructure was manufactured and the sound pressure level of acousticnoise thereof was measured in the same manner as in the case of thefourth comparative example. The result is shown in Table 1.

t1: about 780 μm

t2: about 155 μm

t3: about 155 μm

t2/t1: about 0.2

t3/t1: about 0.2

TABLE 1 t2/t1 t3/t1 SOUND PRESSURE (dB) FOURTH COMPARATIVE 0.05 0.0561.3 EXAMPLE FOURTH EXAMPLE 0.07 0.07 59.6 FIFTH EXAMPLE 0.10 0.10 55.7SIXTH EXAMPLE 0.15 0.15 52.3 SEVENTH EXAMPLE 0.20 0.20 50.2

It is understood from Table 1 that the sound pressure can be made to beno more than about 60 dB by making t2/t1 and t3 /t1 no less than about0.07, for example. Further, it is also understood that, by making t2/t1and t3/t1 no less than about 0.15, the sound pressure is halved fromabout 60 dB, in other words, reduced by about −6 dB, that is, no morethan about 54 dB, for example.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A capacitor comprising: a capacitor main bodyincluding a first main surface and a second main surface which extendalong a longitudinal direction and a width direction, a first sidesurface and a second side surface which extend along the longitudinaldirection and a thickness direction, and a first end surface and asecond end surface which extend along the width direction and thethickness direction; and a first inner electrode and a second innerelectrode provided in the capacitor main body and opposing each othervia a ceramic section; wherein the ceramic section includesferroelectric ceramics; in the capacitor main body, a dimension alongthe thickness direction of a first region where the first and secondinner electrodes are provided is t1; in the capacitor main body, adimension along the thickness direction of a second region that ispositioned on a side of the first main surface relative to the firstregion is t2 ; in the capacitor main body, a dimension along thethickness direction of a third region that is positioned on a side ofthe second main surface relative to the first region is t3; a conditionof t2 /t1>about 0.07 and a condition of t3/t1> about 0.07 are satisfied;and a distance along the width direction from a portion where both thefirst and second inner electrodes of the capacitor main body areprovided to the first side surface is w2 and a distance along the widthdirection from a portion where both the first and second innerelectrodes of the capacitor main body are provided to the second sidesurface is w3, and t2 and t3 are greater than w2 and w3, respectively.2. The capacitor according to claim 1, wherein a condition of about 2.0>t3/t2 > about 0.5 is satisfied.
 3. The capacitor according to claim 1,wherein t2 and t3 are equal or substantially equal to each other.
 4. Thecapacitor according to claim 1, wherein the first inner electrode andthe second inner electrode oppose each other in the thickness direction.5. The capacitor according to claim 1, wherein a dimension of thecapacitor main body along the longitudinal direction is about 0.6 mm toabout 1.8 mm, a dimension of the capacitor main body along the widthdirection is about 0.3 mm to about 1.0 mm, and a dimension of thecapacitor main body along the thickness direction is about 0.3 mm toabout 1.2 mm.
 6. The capacitor according to claim 1, wherein anelectrostatic capacity of the capacitor is no less than about 1 μF and athickness of the ceramic section is no more than about 1 μm.
 7. Thecapacitor according to claim 1, wherein an electrostatic capacity of thecapacitor is no less than about 10 μF and a thickness of the ceramicsection is no more than about 1 μm.
 8. The capacitor according to claim1, wherein a dimension of the capacitor main body in the thicknessdirection is t0, and a condition t1/t0> about 0.6 and a condition of1.2>t3/t2 > about 0.8 are satisfied.
 9. The capacitor according to claim1, wherein a condition of t2/t1>0.15 and a condition of t3/t1>0.15 aresatisfied.
 10. The capacitor according to claim 1, wherein a conditionof t2/t1>0.3 and a condition of t3/t1>0.3 are satisfied.
 11. Thecapacitor according to claim 1, wherein a dimension of the capacitormain body along the width direction is w0, and w0 is about 0.9 to about1.1 times t0.
 12. The capacitor according to claim 1, wherein t2 and t3are greater than w2 and w3 by no less than about 10 μm, respectively.13. The capacitor according to claim 1, wherein t2 and t3 are greaterthan w2 and w3 by no less than about 30 μm, respectively.
 14. Thecapacitor according to claim 1, wherein at least one of w2 and w3 is nomore than about 80 μm.
 15. The capacitor according to claim 1, whereinat least one of w2 and w3 is no more than about 60 μm.
 16. A capacitormounting structure comprising: the capacitor according to claim 1; and amounting board on which the capacitor is mounted; wherein the capacitoris mounted so that the second main surface opposes the mounting board.17. A taped electronic component series comprising: the capacitoraccording to claim 1; and a tape including a plurality of recesses thatare arranged along the longitudinal direction and in each of which thecapacitor is accommodated; wherein the capacitor is disposed so that thesecond main surface opposes a bottom surface of the recess.
 18. Thecapacitor according to claim 1, wherein the first and second mainsurfaces have a different color depth than a color depth of the firstand second side surfaces, such that the first and second main surfacesand the first and second side surfaces are configured to bedifferentiated from one another by the different color depths.
 19. Thecapacitor according to claim 1, wherein a belt-shaped pattern in thelongitudinal direction is provided on the first and second sidesurfaces.